1. Field of the Invention
The present invention relates to a method for producing a magnetic head for a magnetic recording and playback device with which it is possible to record with high density, for example, a video tape recorder (VTR) an da digital audio tape recorder (R-DAT) and so on.
2. Description of the Prior Art
For example, in order to record with high density, it is necessary to make track patterns recorded on magnetic recording medial small. As a method for it, there is the so-called guard bandless recording method in which recording takes place without providing a guard band.
However, as there is no guard band between tracks in the guard bandless recording method, so-called adjacent cross talk which is caused when a magnetic head traces (playbacks) a signal of an adjacent recording track.
Referring to a magnetic head loaded into a home VTR, as shown in FIG. 2, this magnetic head is usually used for both recording and playback, thus, head width (width of a gap) HW of a playback head is formed larger than a recording track pitch in order to ensure compatibility of playback.
Therefore, in case of playback of a recording pattern without a guard band by the magnetic head loaded to the home VTR, an overlap portion G1 of the magnetic gap occurs picks up a signal of a recording track TB adjacent a track TA and the adjacent cross talk is caused.
In a conventional magnetic head, in playing back of an azimuth recorded signal in case of, for example, the home digital VTR, obtained error rates varied from - one figure to + figure even if the playback C/N had been fixed, and the magnetic recording and playback device such as the home digital VTR to which the magnetic head was loaded at the lower limit of variation had to be designed.
Further, the conventional magnetic head had a problem that it was not possible to obtain the error rate enough to play back due to shortage of C/N in recording for a long time that, for example, standard tape feeding speed of the home VTR was two third of usual speed and video tape playback time was 1.5 times of usual time.
On the other hand, it is known that as a track pitch which is a pitch of a pattern recorded on a magnetic tape with high density recording, effect of the adjacent cross talk is larger and it causes degradation of S/N and the error rate.
Therefore, in order to control the effect of adjacent cross talk in playback of in the conventional magnetic head, it is considered that an angle of a track width adjusting groove is formed vertical to a surface opposite to a magnetic gap.
However, the magnetic head having the form is not preferable in point of recording and playback because a cross section of a magnetic core in the neighborhood of a magnetic gap.
Further, in a conventional method for producing the magnetic head, projections for forming the magnetic gap of a pair of magnetic core half bodies are not perfectly matched to both ends, and displacement of the ends of the projections for forming the magnetic gap of a pair of magnetic core half bodies occurs. Though it is known that this displace causes the adjacent cross talk, it is not clear that relation between the displacement and the adjacent cross talk.
Therefore, by forming, for example, the angle of the track width adjusting groove large, that is to say, the V-type groove of a large angle, it is considered to match to the both ends of the projection for forming the magnetic gap of a pair of magnetic core half bodies as perfectly as possible.
However, when making the angle of the track width adjusting groove large, the method for producing the conventional magnetic head had a problem that process yield was remarkably degradated to match the magnetic gap only at the edge of the track width adjusting groove.
The present invention was proposed considering the conventional technical problem and an object of the present invention is provide a magnetic head producing method for producing a magnetic head that is possible to control effect of adjacent cross talk less with the good process yield.